Ingress Node Packet Prioritization for Load-Balancing Network Congestion

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Solution Overview

Problem

Load-balancing networks face challenges in limiting egress traffic to prevent congestion, as existing solutions like token bucket and leaky bucket policing result in TCP throughput reductions and queuing delays, and are inefficient in managing hose constraint violations, especially when multiple services share links and broadcast services increase egress traffic loads.

Innovation Solution

The method involves determining the egress node for each packet and assessing congestion conditions, allowing packets destined for congested egress nodes to have different queuing priorities, with the option to drop or mark packets at the ingress node to manage egress traffic and enforce hose constraints, thereby preventing congestion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If token bucket egress policing is used to limit egress traffic, then hose constraint is satisfied, but TCP throughput is reduced

Engineering Contradiction:

Improvehose constraint satisfactionVSAvoidTCP throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by determining egress node congestion status before packets are forwarded through the load-balancing network. Ingress nodes query egress nodes for congestion information in advance, and based on this pre-acquired information, packets are marked with appropriate queuing priorities before entering the network, preventing congestion proactively rather than reacting to it after overflow occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where egress nodes continuously monitor their own congestion status and provide this information back to ingress nodes. This feedback loop allows ingress nodes to adjust packet marking and queuing priority assignments dynamically based on real-time egress node conditions, enabling adaptive traffic control that maintains hose constraints while optimizing throughput.

Inventive Principle:

Principle #23Feedback

2Reliability

If leaky bucket egress policing is used to limit egress traffic, then hose constraint is satisfied, but queuing delay increases

Engineering Contradiction:

Improvehose constraint satisfactionVSAvoidqueuing delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #23Feedback

3Reliability

If link speed is set equal to egress hose constraint, then hose constraint is satisfied, but bandwidth is wasted

Engineering Contradiction:

Improvehose constraint satisfactionVSAvoidbandwidth utilization

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making packet queuing priority assignments dynamic rather than static. Instead of setting fixed link speeds equal to hose constraints, the system dynamically adjusts packet treatment based on real-time egress node congestion status. Packets are marked with different queuing priorities at ingress nodes based on current egress conditions, allowing the network to adapt traffic flow dynamically to available capacity, thereby maximizing bandwidth utilization while still satisfying hose constraints.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If broadcast services are replicated at intermediate nodes, then service coverage is improved, but egress traffic load increases causing hose constraint violations

Engineering Contradiction:

Improveservice coverageVSAvoidhose constraint satisfaction

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7539133B2Method and apparatus for preventing congestion in load-balancing networks

Publication Date: 2009.05.26 WSOU INVESTMENTS LLC

AI summary

The invention includes a method and apparatus for processing traffic in a load-balancing network comprising a plurality of nodes. The method includes determining an egress node associated with each of a plurality of packets of a traffic flow received at an ingress node of the plurality of nodes, determining, for each packet, whether a congestion condition exists on the egress node, and processing the packets such that packets associated with egress nodes for which the congestion condition does not exist have a different queuing priority within the load-balancing network than packets associated with egress nodes for which the congestion condition exists. The ingress node on which the traffic flow is received is adapted for splitting the traffic flow into a plurality of traffic flow portions independent of the egress node by which each packet is scheduled to exit the load-balancing network.